Pipette



Patented Aug. 31, 1937 UNETED TATE PATENT QFFIQE 1 Claim.

My invention relates generally to pipettes, and particularly to a device of this type which involves a manually operated compression forming and releasing unit, and an important object of my invention is to provide a simple and eflicient arrangement of this character.

Another important object of my invention is to provide in a pipette, a manually operated compression forming and releasing unit which can be mounted on or connected with standard pipettes.

Other important objects of my invention will be apparent from a reading of the following description taken in connection with the drawing,

wherein for purposes of illustration 1 have shown preferred embodiments of my invention.

In the drawing:

Figure 1 is a general side elevational view of an embodiment of my invention.

Figure 2 is an enlarged longitudinal sectional view taken through Figure 1.

Figure 3 is a horizontal sectional view taken through Figure 2 approximately on the line 33 and looking downwardly in the direction of the 5 arrows.

Figure 4 is a View similar to Figure l of another embodiment of my invention.

Referring in detail to the drawing, and particularly to the embodiment of the invention shown 30 in Figures 1 and 2, the compression unit which is generally designated 5 comprises the glass or other suitable material tube 6 which has an open lower end 'I on which is threaded as indicated by the numeral 8 a metallic or other suitable 5 material cap 9 which acts as a retainer for the lower end of the helical expanding spring Ill. The cap has in its center an opening I l.

The upper part of the tube or cylinder 6 has therein a partition l2 produced by a thickening of 4 the wall of the tube, which partition defines the small longitudinal passage l3 and the relatively larger plunger barrel M in which the plunger or piston l5 works.

The piston is fastened to the upper end of the 5 leg I 6 of the plunger ll whose other leg works in the passage is. The upper end of the passage I3 is extended as indicated by the numeral l8 and closed by a threaded cap l9 through which the notched portion 20 of the plunger operating 50 handle ll works. The upper end of the helical spring in has a member 2| which seats it on the bight portion of the plunger operating rod ll as clearly shown in Figure 2.

The upper end of the passage [4 or plunger 55 barrel is tapered and curved as indicated by the numeral 22 to enter the top of the pipette 23 which has the usual tapered lower end 24.

The embodiment of the invention shown in Figure 4 is the same as that described except that the elbow 25 while corresponding in shape to 5 the elbow 25 of the already described embodiment is cut off at the point 25, where it is provided with a ground joint 21 to receive the ground and tapered upper end 28 of a standard pipette 23, where it is desired to adapt the device of the 10 invention for operation of standard pipettes and the like. The upper end of the plunger operating rod has a button 29 facilitating its operation. The tube 6 acts as the handle for the device. If desired the connection between the pipette 23' 15 and the elbow 25 in the embodiment of the invention shown in Figure 4 may be effected by the use of the common laboratory hollow rubber stopper or any suitable connector to make the two units rigidly connected to form the complete 20 instrument.

To operate the device of the invention in measuring or transferring liquids from one container to another, the thumb button 29 is pressed downwardly so as to force the piston 15 down- 5 wardly in the piston barrel l4 while the lower end of the pipette tube 23 or 23' is in the solution, so as to engage one of the notches 28 with the cap l9. When the transfer of the instrument has been effected, the button 29 is released 30 by disengaging the notch from the cap !9, and the coil spring Ill will force the piston to its original position. so as to empty the hollow glass tube or pipette 23. The last drop which may remain in the pipette tip 24 may be removed by 5 first compressing the button 29 slightly to allow the piston to return to a higher level than the level from which the liquid was taken up.

Although I have shown and described herein preferred embodiments of my invention, it is to be definitely understood that I do not desire to limit the application of the invention thereto, and any change or changes may be made in the materials and in the structure and arrangement of the parts, within the spirit of the invention l tending into the larger cylinder, a piston on the shorter portion of said plunger within the larger cylinder, and a compression spring in said upper end of the pipette tube tensioning said plunger against movement in the direction tending to 5 draw liquid into said pipette tube.

FRED L. HICKS. 

